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Convert Winchester Model 70 Long Action Bolt to Magnum?

calinb

Plastic
Joined
Dec 15, 2010
Location
N. Central Idaho, USA
I have a post-64 push-feed M70 (not the more recent "CRPF" and I'd like to convert it to a magnum to run a wildcat cartridge in a new Krieger barrel. I'm just a hobby gunsmith so I don't know how the bolts differ and I can't even find good push-feed photos online. Can I just open up the bolt face and then install a magnum extractor?

Thanks for the help!

-Cal
 

calinb

Plastic
Joined
Dec 15, 2010
Location
N. Central Idaho, USA
Thanks! I'll call PTG and see if they have any. MGW has them (factory OEM parts) but they are a bit over $300. Maybe I'm wrong (and I probably am) but it seemed to me that opening up the bolt face on my LA bolt would not be any more difficult than fitting a brand new bolt to the action.

I've been watching for a used bolt but haven't seen many and none that I wanted to buy yet.
 

akajun

Hot Rolled
Joined
Jul 1, 2011
Location
Brusly, LA
On a push feed that’s prob all it is, just like a Remington, all the ejector pin holes are the same
You’d have to put a new 7mm mag extractor in it but that’s a cheap part
 

1yesca

Stainless
Joined
Jun 1, 2004
post 64 is that the one that has the slotted cut in the side of the locking lug that the extractor sets in with the spring loaded plunger ? if so the only thing that may pose a problum is the location of that plunger hole is it in the same spot for a mag size base as it is for a std. 30-06 size ? as far as opening up the bolt face there are a number of ways to get there 06 base is about .473 if i remember right so what is your bolt face now compared to the ? do the same with the mag. or if there is a gun store that you deal with and they have a used gun for sale will they let you take a few measurements ? so if the plunger hole is in the same place and the deep is the same and the extractor is setting at the same place [you can go down a bit as far as the bolt face goes and if so you would have to shorten the firing pin ]then it looks like all you would have to do is machine the counter bore bigger and cut back your extractor or install one for a mag.
 

RoundHouse M&F

Plastic
Joined
Oct 12, 2020
Location
Speedwell
Yup, just pop the pin holding the ejector, and pull the extractor off and it should be just like a Rem700. Skim the bolt face, bore to .540" Dia (standard magnum)and your good. Holding it will be the fun part unless you have a viper barre/truing fixture, or a big throat lathe chuck

I had a M70 PF that was smooth as glass. I was going to make it into a 300prc, but i needed Cip mag length so I ended up buying and truing a Rem 700 action and building on that (still a good gun tho :))
 

calinb

Plastic
Joined
Dec 15, 2010
Location
N. Central Idaho, USA
Thanks for the information and advice, everyone. As always, members of this forum have really helped me out!

On a push feed that’s prob all it is, just like a Remington, all the ejector pin holes are the same
You’d have to put a new 7mm mag extractor in it but that’s a cheap part
I'm thinking about getting this extractor: Winchester 70 push-feed extractor, magnum calibers #1900A0690 (for short magnums, bevel bottom front corner)


getting the magazine to feed properly is generally the hardest part
I hear ya', John. I've spent hours getting even box stock factory rifles and mags to feed well (M70 WSSM and Savage 93 17HMR). I prefer metal magazines and this one will have AI mags and CDI bottom metal. I've found that metal mags provide more adjustment options than plastic mags.

post 64 is that the one that has the slotted cut in the side of the locking lug that the extractor sets in with the spring loaded plunger ? if so the only thing that may pose a problum is the location of that plunger hole is it in the same spot for a mag size base as it is for a std. 30-06 size ? as far as opening up the bolt face there are a number of ways to get there 06 base is about .473 if i remember right so what is your bolt face now compared to the ? do the same with the mag. or if there is a gun store that you deal with and they have a used gun for sale will they let you take a few measurements ? so if the plunger hole is in the same place and the deep is the same and the extractor is setting at the same place [you can go down a bit as far as the bolt face goes and if so you would have to shorten the firing pin ]then it looks like all you would have to do is machine the counter bore bigger and cut back your extractor or install one for a mag.
Yes--this is the bolt with the extractor cut in the locking lug. I have a local gun shop that would typically have a M70 magnum PF for measurements. These days, who knows. Used M70 and Rem 700s seem to be in short supply. It sounds like the extractor hole is the same size and I think the hole is in the same place relative to the center of the bolt face in both non-mag LA and magnum bolts too, but I'll double check its position.

Yup, just pop the pin holding the ejector, and pull the extractor off and it should be just like a Rem700. Skim the bolt face, bore to .540" Dia (standard magnum)and your good. Holding it will be the fun part unless you have a viper barre/truing fixture, or a big throat lathe chuck

I had a M70 PF that was smooth as glass. I was going to make it into a 300prc, but i needed Cip mag length so I ended up buying and truing a Rem 700 action and building on that (still a good gun tho :))
Thanks for the explicit guidance, RoundHouse! I may have to make some kind of bolt fixture. I've got a Bergara B14 (Remington 700 clone) in 300 PRC. CIP length does seem to be tough nut to crack in a M70.
 

RoundHouse M&F

Plastic
Joined
Oct 12, 2020
Location
Speedwell
I made a clone of the viper fixture and excluding my time in turning and milling it i had $80 in aluminum which i also used the leftover to make a spider for centering barrels on the back side of my headstock, and $20 in brass tipped set screws. Its pretty straight forward to make and i like how it works for bolts, receivers, and short barrels

However if you don't want to invest much in this. Iv seen people make a mandrel that threads into the back of the bolt, screw it tight into the bolt, lightly skim the shank so it runs true with the bolt body, then grip on the shank and support the end with a steady rest. This way will probably require alot of indicating to make sure the bolt is running straight and not offfset like cutting an od taper with the tailstock shifted. This is why i went ahead and made the viper to me it was just easier in the long run if i did another rifle or if i had short barrels that didn't reach thru the headstock
 

calinb

Plastic
Joined
Dec 15, 2010
Location
N. Central Idaho, USA
I have Speedy's drawings for bolt fixture. Tried to post, but it is in PDF format. I can email it.

PM sent. Thank you!

I made a clone of the viper fixture and excluding my time in turning and milling it i had $80 in aluminum which i also used the leftover to make a spider for centering barrels on the back side of my headstock, and $20 in brass tipped set screws. Its pretty straight forward to make and i like how it works for bolts, receivers, and short barrels

<snip>
This is a hobby for me so I'll enjoy making the fixture as much as I'll enjoy using it. Thanks for the details of your experiences too!
 

clarkmag

Aluminum
Joined
Apr 24, 2013
Location
Mercer Island WA
I got a Winchester M70 7mmRM made in 1968 with Redfield scope Post 64 m70 7mmRM 1968 20211211_220110.jpgat a pawn shop for $360 +$34 tax on 12/29/2016

I have bought 8 other M70s that are pre 64. They cost me twice as much.
 

calinb

Plastic
Joined
Dec 15, 2010
Location
N. Central Idaho, USA
I got a Winchester M70 7mmRM made in 1968 with Redfield scope at a pawn shop for $360 +$34 tax on 12/29/2016

I have bought 8 other M70s that are pre 64. They cost me twice as much.

They've about doubled in price over the last couple of years at the pawn shops I've visited recently...when you can find a Model 70 at all (or Rem 700 too)!

I have Speedy's drawings for bolt fixture. Tried to post, but it is in PDF format. I can email it.
The fixture looks very useful, and versatile (maybe receiver blueprinting in some cases). Like the inventor's name, it appears to also be quite speedy to setup.

I have thought of another very simple way to do the job I have at hand though. How about a chuck spacer plate containing a cutout for the bolt handle? It would need to be about 0.55" thick for my chuck and spindle. Or maybe just a partial plate but more than just simple standoffs probably so there's enough precision surface to maintain chuck squareness, if not perfect concentricity, to be dialed-in with the 4-jaw chuck, of course.

Load the bolt into the chuck from the backside and then attach the chuck to the lathe spindle with the slotted chuck to spindle spacer.

I'm very interested in what you and others here think about this idea.

backload_bolt.jpg

Thanks again!

-Cal
 








 
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